The plakortones, novel bicyclic lactones from the sponge Plakortis halichondrioides: Activators of cardiac SR-Ca2+-pumping ATPase

Abstract Bioassay-guided fractionation of the EtOAc extract of sponge Plakortis halichondrioides yielded four novel bicyclic lactones, plakortones A, B, C, D and a novel acid, plakortide E ( 3, 4, 5, 6 and 7 ). The structures, including stereochemistry, of these compounds were established by interpretation of spectral data. Plakortones A-D ( 3–6 ) comprise a novel class of activators of cardiac SR-Ca 2+ -pumping ATPase which were found to be active at micromolar concentrations As part of an SAR study, the α and β diols 9 and 10 of plakortone D were prepared using Sharpless AD procedure.